High-frequency inductive coupling



July 12, 1949. 59,, H FE 2,475,829

HIGH-FREQUENCY INDUGTIVE COUPLING Filed July 16, 1946 Patented July 12,1949 2,475,829 HIGH-FREQUENCY INDUCTIVE COUPLING Pieter Harm Fennema,Eindhoven, Netherlands, assignor to Hartford National Bank and TrustCompany,

Application July Hartford, Conn, as trustee 16, 1946, Serial No. 684,087

In the Netherlands January 28, 1943 Section 1, Public Law .690, August8, 1946 Patent expires January 28, 1963 3 Claims. (Cl. 171-119) Thisinvention relates to a combination of at least two coils arranged in acylinder. When such combinations are manufactured in large quantities,it is in most cases necessary for the properties of the combinations tobe made exactly equal to one another. In order to be able to adjust therelative inductance of these coils, a construction was previouslysuggested in which the two coils wound on frames are arranged inside thecylinder and in which the portion of the cylinder at the height of themiddle between these coils comprised a depressed groove. This grooveconstitutes somewhat of a diaphragm whereby the field coupling the coilscould be reduced. It has been found that the possibility of adjustmentin this construction is too small.

In another known construction the coils are mounted displaceably withinthe shield can or the can consists of two parts, one of which slideswith respect to the other, each part carrying one of the coils. Thistype of construction is relatively complicated and expensive.

The object of this invention is to provide a simple and inexpensive coilsystem in which ample control oi the coupling between coils is providedby'varying the distance between the coils.

According to the invention two coils are each secured at a differentlocation on the wall of a cylinder with the wall separating the coilseasily deformable in order to alter the distance between the cells.

The invention will be explained more fully by reference to theaccompanying drawing showing, by way of example, a section of acombination according to the invention. a

In the vicinity of the ends of a metal cylinder 1 are arranged twodish-shaped insulating rings 2 which are, for example, of artificialresin. The cylinder comprises two grooves 4 in the vicinity of theadjacent edges of the insulating rings, whereas at the other side of thedish-shaped rings the cylinder is flanged in 5. These rings are thusfirmly secured in the cylinder. Two little tubes 6, for example ofpertinax, are clamped in the dish-shaped rings. The coils l are wound onthese little tubes, while little rods 8 of high-frequency iron arefastened in the said tubes by means of a small quantity of compoundindicated by '9; The lower dish-shaped ring 2 comprises a projectingpart II) which is provided with screwthread and carries a nut ll pressedfrom sheet metal. With the aid of these parts the combination isfastened on a chassis-plate l2. As can be seen from the drawing, thedistance between the two coils is determined by the shape of thecylinder between these coils. This portion of the cylinder comprises notonly grooves 4, by means of which the .coils are fastened, but also athird groove IS. The latter is provided when the combination iscompleted. To this end it is placed on a device which is constituted bya combination of a lathe by means of which the groove may be providedand a measuring device by means of which the electrical properties ofthe combination may be ascertained. During the depression of groove l3,the changes in the electrical properties of the coils may thus befollowed.

The groove may also be provided preliminarily in the cylinder and theelectrical properties may be changed afterwards by depressing orextending the cylinder.

It is evident that methods of deformation of the cylinder other than bymeans of a depressed groove are also possible. The cylinder couldcomprise a certain number of apertures l4, placed in a circle, in suchmanner that the two halves are connected by means of a certain number ofnarrow metal strips 15 and can be displaced relatively to each other bydeforming these strips. When such apertures are provided, however, itwill generally be necessary to provide an additional shield.

What I claim is: 1. A coil system comprising a hollow cylindricalmember, a plurality of coil members each secured to a separate portionof the inner wall of said cylindrical member, and an easily permanentlydeformable integral wall portion of said cylindrical member separatingeach of said coil members for altering the distance between the saidcoil members.

2. A coil system comprising a hollow cylindrical member, a plurality ofcoil members each secured to a separation portion of the inner wall ofsaid cylindrical member, and an easily permanently deformable integralwall portion of said cylindrical member provided with an annular grooveseparating each of said coil members for altering the distance betweenthe said coil members.

PIETER HARM FENNEMA.

anrmancns crrnn The following references are of record in the file ofthis patent:

5 UNITED STATES PATENTS Number Name Date 2,914,820 Snider Sept. 17, 1935R0 FOREIGN PATENTS Number Country Date 139,211 Great Britain Sept. 23,1920

